A method for real-time testing of a control unit for an internal combustion engine using a simulator is provided. The control unit and the simulator are connected to one another by a first data channel. The control unit transmits engine control data to the simulator through the first data channel and the simulator calculates engine state variables in real time on its first simulator processor with a first sampling step size and transmits at least some of the engine state variables to the control unit. Thus, selected engine state variables can be made available at a different frequency, and in particular at a higher frequency, than is possible by the first sampling step size of the first simulator processor, in that the simulator calculates at least one specific engine state variable using a partial engine model and with a second sampling step size different from the first sampling step size.